Water Pump on Lexus 2007 RX 350

The timing chain operates the camshafts. The water pump is probably driven by the accessory belt.

I wouldn’t touch the pump unless it starts leaking.

The reason timing-belt-driven water pumps are replaced is because all the labor is in the belt replacement, and it’s just good sense to install a new pump at the same time.

This is not the case with your engine.